[Che]

I'm having trouble getting my Sierra's headlight relays firing.

I have three wires as drawn from the modular socket thingy on the back of the headlight, so i'm guessing one is high beam, one low beam, and the other a ground... these three seen in the pics:



The two being red i'd have assumed to be hi and low beam. But - the white has constant power, neither of the red wires register anything with a circuit tester as I switch through the detents on the light/indicator stalk. I'm getting the same from the passenger side headlight loom.

Before I pull the dash to see what's going on, can anyone confirm which wires colours go where?

[whincup]

sierra's are negative switched (someone can explain it better) but this pic is the best explanation:



have a read of this thread. starts off about spotties but moves into headlights, that pic is taken from page 3

viewtopic.php?f=17&t=1108&start=60

basically, connect the red to pin 85 of the low beam relay, red with white trace to pin 85 of high beam relay, then white with red trace to pin 86 on both relays...

Edit: the red with white trace is low, red is high. sorry...

[Che]

Thanks Whincup... I worked it out in the end (EDIT - I thought I worked it out). I was relying too much on the circuit tester, not enough on Royces schematic from the 'good tech' forum post you've linked above

[whincup]

i did exactly the same thing... thought i could just use one trigger wire for each relay then earth to the chassis. of course, it didnt work. bit of reading royces knowledge and all good.

[Che]

OK, surprise surprise, a fruk up... I can't seem to get my low beams firing.

Circuit is 100% correct as to Mitchy/Royce's diagram from the 'wiring up spotties' guide. Parkers work fine, so too high beam and spotties. Fuses are in, circuit is live, earthing is good, all connections are solid, relay has been tested to work fine.

Where's the ghost in my system?

[Che]

Oops, seems it's my driver's side loom... feeding from the passenger side headlight connection there's no problem at all.

So... being negative switching - how can I trace wiring fault back to the source?

[Che]

This sucks... had em all working, taped up the looms for the second time, now the high beam and spotties won't work.


Grrr!

[Che]

Is there a reason why I shouldn't splice into the headlight loom from the other side of this connector under the dash? I seem to have a ghost in these wires, so I want to go back as far as I can to try rid the fault

[whincup]

no reason you shouldnt... but are you sure the problem is after that part? can you use a continuity tester to make sure theres no breakages between this and the other wire? can you hear the relay click? are both of the original headlight fuses intact?

[Che]

I just posted this up in the 'wiring up spotties' tech article, but I might move it here:

I'm having a hell of a time with this and spent two days trying to get it right. I've double and triple checked, and my loom upgrade is 100% to spec as per the various diagrams listed, grafted into the stock loom as it should be, but things are still awry.

Parkers and low beam work as they should, but try and flick for high beam and it all goes dead. Rotate the indicator stalk back to 'off' and flick my spottie switch and I can fire up my HIDs, but turn the stalk for low or high beam and again - it all goes dead. Funnily, if I switch around the wiring on the back of my spottie switch the high beams work (not the HIDs)... but again - turn the stalk and it all goes dead. My spottie switch is three pin (ground/load/supply) with an 'on' LED and as far as I know it should be OK for the job.

So, all the lights work, all the relays work, but never at the same time. Is it obvious to anyone what's going on, or has anyone got any troubleshoots?

[alien]

lol i'd just order one of royce's plug n play looms... way easier and saves dealing with 20yr old wiring that someone else has probably mucked around with.

[royce]

youll never get a light up switch to work on something that switches to ground (well you can but your head will explode?)

go back to teh start, you still have the stock headlight loom and plugs un molested dont you? plug them both back in and make sure both headlights work, that takes out any loom or dipper switch dramas

then plug your loom back in and see if you get high and low, if one misses swap relays, if the same light misses youve got a wiring prob, check that relay for power on pin 30 and 86 and that 85 switches to earth when you dip to teh light, a test light across pin 85 and 86 will make this easier

By now youve found the problem

[Che]

Thanks Royce, good advice. I'll do that right now

[Che]

Well, easy test - I plugged the passenger side loom in and grafted the left side back on... no dice. Parker lights are all that works, no low/high beam either side. It's all indicating on the dashboard, but no lights out front... to tell the truth i'm not sure I ever saw the headlights working on this Sierra... maybe they never did... I had it in parts after a week.

So... back to the drawing board.

I'll pull out the multimeter in the morning and do a bit of continuity testing through the circuits, see what I have on my hands here.

[longzooki]

Is there any need to use the stock loom? im trying to wire them pos switched so i can groundclose to the globes while upgrading the wiring,relays and fuses

[Reubs]

royce wrote:

youll never get a light up switch to work on something that switches to ground (well you can but your head will explode?)

My head must have exploded...

I used Narva part no. 60049BL for an LED lighty uppy switch for spotties in my Sierras (and now my Vit).

Use this diagram - (please ignore the wire size details). Note the colours of the wires...

[Reubs]

If you can't follow all the extra stuff in the first attachment above - just refer to the second attachment for spotlight wiring only...